Heart rate monitors and blood oxygen monitors are medical devices used to measure heart rates and blood oxygen levels in real time and/or to record such measurements for later study. Some heart rate monitors use electrodes in contact with a user's skin to measure small electrical signals that are generated by the user's heart as it beats, and other heart rate monitors use light (e.g. IR light) to measure small light fluctuations due to the user's blood circulation. Blood oxygen monitors typically use light (e.g. red light and IR light) to measure the oxygen content of the blood.
Most heart rate monitors which measure light fluctuation are transmissive-type devices which include an infrared (IR) light emitting diode (LED) and a separate photodetector. The IR LED is typically positioned on one side of a finger clip and the photodetector is typically positioned on the other side of the finger clip. In use, the IR light generated by the IR LED is transmitted through the finger, where it is modulated by the blood flow, and is then detected by the photodetector for processing.
Most blood oxygen monitors are also transmissive-type devices which include a red LED, an IR LED and a separate photodetector. The red LED and IR LED are typically positioned on one side of a finger clip and the photodetector is typically positioned on the other side of the finger clip. In use, red light generated by the red LED is transmitted through the finger then is detected by the photodetector for processing.
Medical grade heart rate monitors and blood oxygen monitors have been combined in the past. Even so, they tend to be bulky, cumbersome and expensive. In particular, the medical grade electronics of the monitoring apparatus are typically housed in relatively large chassis and often require filtered wall power to operate. Furthermore, long and cumbersome cables are used couple the monitoring apparatus of the prior art to the finger clips.
Because of the aforementioned problems of traditional medical monitoring equipment, a number of portable, battery powered devices have become available. For example, heart rate monitors including electrodes have been built into a number of devices including wrist watches, exercise equipment, and portable electronic devices such as smartphones. There are also finger clip type transmissive sensors that can be coupled to, for example, a smartphone for detecting heart rate. While less expensive, such devices are also less versatile and tend to have fewer features.
These and other limitations of the prior art will become apparent to those of skill in the art upon a reading of the following descriptions and a study of the several figures of the drawing.